The present invention relates to a utility knife and more particularly to an improved utility knife which is capable of having a knife blade extend from its forward end to cut open boxes, cartons, etc..
In the past, utility knives have been assembled from two matching body halves within which there is provided a knife blade. The two matching halves are adapted to interfit with each other to form the body of the tool and to be held together by any suitable means, such as screws, snap locks, etc. The two matching halves have spaces at their front ends in order to form an open mouth. Mounted within the matching halves of such utility knives is a blade carrier with a blade thereon which is adapted to be moved forwardly by a manually operable pushbutton or the like in order to project the blade through the open mouth to permit the tool to be used. The pushbutton is moved rearwardly to retract the blade within the two matching halves when the tool is no longer in use. Examples of such retractable utility knives are disclosed in U.S. Pat. Nos. 4,930,218; 5,031,322 and 5,086,562, the descriptions and disclosures of which are incorporated herein, by reference.
It has become desirable for safety considerations for the knife blade in such utility knives to be automatically retracted within the holder. In such utility knives, the release of the manually operable pushbutton will automatically retract the blade to a position within the confines of the two halves so that the blade cannot be inadvertently left in its extended exposed position and there is no danger of any injury resulting from such an exposed blade. Examples of such automatically retractable utility knives are disclosed in U.S. Pat. Nos. 3,906,627; 2,550,346; 4,139,939; 5,012,581 and Canadian Patent No. 671,327.